Epidemiological evidence quartz, silica and lung cancer

Project No. BIA 0061

Status:

completed 12/2002

Aims:

The association between exposure to silica (quartz dust) and lung cancer has been the subject of discussion for some time in occupational safety and health. Although a number of epidemiological studies have now been produced on the subject, the scientific conclusions remain unclear even for experts. Interpretation of the results has proven particularly difficult and controversial. Even following the classification of quartz as a human carcinogen, many questions remain unanswered with regard to the dose-effect relationship and definition of a limit value, since exposure, silicosis status, and important confounders and other bias factors such as smoking or radon exposure have not been systematically taken into account. The intention of this project was to provide a comprehensive summary of the pertinent epidemiological literature.

Activities/Methods:

An extensive literature search was performed to identify the appropriate studies. The studies were compared to other reviews, grouped into cohort and case-control studies, and classified by industrial sector. The mean relative risks of the study results were calculated. The influence of silicosis status and smoking were subjected to particular analysis in the general synopsis (quality-based critical review, QBCR).

Results:

The results of the meta-analysis indicate that an increase in lung cancer risk among silica exposed workers is limited to silicotics. For groups subject to high exposure, an increased risk of lung cancer is observed which cannot be explained solely by smoking or other confounders. For further research, both smoking and silica exposure must be quantified.